A boost power converter is one type of switching mode power supply which converts an input direct current (DC) voltage to a higher, output DC voltage of the same polarity. Boost power converters may operate in a discontinuous conduction mode, where current flow through the inductor is zero for a portion of the switching cycle. When the inductor current reaches zero, the power converter will ring or oscillate due to the effects of parasitic capacitance in the power switch and rectifier diodes. This ringing can destabilize the control loop of the converter and decrease conversion efficiency. Furthermore, when the boost converter is used for active power factor correction, the ringing can introduce spurious harmonics in the line current, resulting in an undesirable reduction of the power factor.
One solution to this problem is to use a passive resistor-capacitor (RC) network connecting the converter switch node to ground which dampens out the oscillations. This approach, however, requires a relatively large capacitor which consumes too much die area, in the case of an integrated solution, or additional external components, in the case of a discrete solution. Another approach is to use an active damper (i.e., a low side damping switch) between the converter switch node and ground, but this wastes power and decreases the converter efficiency.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.